motorized valve, powerhead or motor - which has failed?

[skyflyer]

I have established that boiler wasn't firing up as no current from the microswitch in the motorized valve.

I also notice that when the valve is opened manually, the microswitch isn't triggered; only when the valve is opened by the motor does it travel that little bit further to trigger the microswitch.

Having never examined one of these before, I have no idea is the above description is correct or if it is a fault - should manually opening the valve, trigger the m/switch?

The synchron motor turns, although I havent checked it under load. It turns very slowly however, maybe 5-8 rpm ?. I am at a loss as to what stops the motor turning, does it keep the power on continuously whilst the valve is open and 'slip' somewhere or does the microswitch cut power to the motor at the same time as it supplies power to the boiler?

Anyway, what i really want to know is do I replace the motor, the powerhead or the entire valve?

Any thoughts anyone. Cheers

 

[nickso]

should manually opening the valve, trigger the m/switch?

no

The synchron motor turns, although I havent checked it under load. It turns very slowly however, maybe 5-8 rpm ?. I am at a loss as to what stops the motor turning, does it keep the power on continuously whilst the valve is open and 'slip' somewhere or does the microswitch cut power to the motor at the same time as it supplies power to the boiler?

Anyway, what i really want to know is do I replace the motor, the powerhead or the entire valve?

they always turn slow. the power is constantly on to the motor when there is a demand, no cut out. if the motor turns but it doesnt hit the microswitch at the end, replace the motor after making sure the spindle it turns is free, you should be able to turn the spindle by hand.

 

[skyflyer]

thanks, but can you clarify:

by 'spindle' I assume you mean the actual valve spindle that sticks out of the 'brassware', when you remove the powerhead, and not the spindle (cog) of the synchron motor?

If the valve spindle wont turn byhand then I assume that means the valve itself is knackered - probably furred up - and the whole thing then has to be replaced?

To be honest, looking at costings, the powerhead is almost as expensive as the entire valve assembly. If it's not just the motor at fault I might as well replace the entire head

 

[gas4you]

You're probably better off if you replace the entire valve. Will entail a bit more work with draining some water out of system, but worth it in the long run.

 

[nickso]

i disagree dave, especially for a diyer as its far more work and can cause added complications.

what model valve is it? the spindle is indeed the shiny bit that protrudes from the brass body.

 

[skyflyer]

well, events have overtaken things! Basically I thought that it would be simpler to replace the whole valve and be done with it, especially as the local merchant didn't have the powerhead alone and would have to order it in.

Fortunately whoever installed the system fitted gate valves like they were going out of fashion so it was relatively easy to isolate most of the system, leaving just one pipe to freeze up, to avoid a complete draindown.

Being curious I took the old valve apart and it was well and truly furred up, so probably as well to replace it.

Thanks everyone for your suggestions; in the end the need to re-instate the hot water in the house overtook the need to keep costs down!